Research tracking the health and happiness of the UK's children

Tag Archives: Asthma

Public health bodies put a lot of effort into encouraging mothers to breastfeed, and for good reasons. Successive studies have shown breastfeeding has a range of health benefits, including a lower risk of wheezing illnesses, which can be linked to asthma. But which of these illnesses are most likely to respond? Is a breastfed child less likely to develop wheezing after age five, or age seven, for instance? Or is the protective effect mainly measurable only in younger children? Professor Maria Quigley from the National Perinatal Epidemiology Unit at the University of Oxford, along with colleagues at Oxford and UCL, has been looking at how and when breastfeeding is associated with wheezing.

Asthma is the most common chronic condition affecting children and young people in the UK. It’s the most common reason why children are admitted to hospital, and sadly each year a few still die from the condition. According to the British Lung Foundation three children in every hundred under the age of five have been diagnosed with asthma at some point; and by age 10 that figure rises to one in 10.

There’s no cure, and so the priority for public health bodies has been to understand the disease better, to manage it better and to learn more about the factors that can protect us from it. One such protective factor is breastfeeding: two recent pieces of research have shown there is a lower risk among breastfed children, but that the effect is stronger among the very young – both for asthma and for wheezing, which has many causes and which does not necessarily develop into asthma.

Childhood wheezing can follow a variety of patterns – it can set in early but clear up before adulthood, for instance, or it can start later but continue into later life. Some wheezing will start in childhood and will continue.

Millennium Cohort Study

We wanted to look at how breastfeeding might affect these different types, so we used data from the Millennium Cohort Study, which has followed the lives of almost 19,000 children born in the UK between September 2000 and January 2002. Their parents were interviewed when they were 9 months old, and again when they were 3, 5, 7 and 11 years.

Our study focused on just over 10,000 children who were seen at all of those points and who were the product of single as opposed to multiple birth. Mothers were asked whether they had tried to breastfeed, and for how long their children had been breastfed.

Among our sample, seven out of 10 children had been breastfed: a little more than one in ten of the study sample for less than a week; a fifth for between one and three weeks, just over one in six for three to six months and around a quarter for six to nine months.

We found that at age 9 months, 6.5 per cent of children had a history of wheezing. At age 3 years, 19.5 per cent had such a history in the past year. As the children got older, though, this proportion decreased – 16 per cent at age five, 11.8 per cent at age seven and 11.4 per cent at age 11.

Overall, 37 per cent of children had suffered from wheezing at least once between 9 months and 11 years. A little under a fifth (18.8 per cent) had wheezing at younger age which cleared up when they got older, while 6.2 per cent had wheezing which started later and 11.8 per cent had persistent wheezing.

Feeding and wheezing

When we looked at the association between breastfeeding and wheezing, we found the children who had been breastfed for longest were less likely to suffer from wheezing.

But this effect lessened with time. For example, those breastfed for six to nine months were less likely to wheeze between the ages of nine months and five years, but by the age of 11 this group had no significant advantage over those who were breastfed for less time.

What does our study tell us about the relationship between breastfeeding and wheezing? The picture is a complex one. There are many causes of wheezing and of asthma, and those causes change over time. So in order to draw firm conclusions about cause and effect, we would need a much more complex dataset. It would be interesting, for instance, to look at clinical information on children’s allergies or their lung function.

But what we can say is that age matters – in order to understand how breastfeeding affects the development of wheezing during childhood, we must take a longer and more nuanced view.

Asthma and wheezing illness are some of the most common childhood illnesses, and appear to have been on the rise in many developed countries. In the ongoing battle against them, considerable research has looked at the links with the surroundings we live in. From the effects of cold weather to dusty homes and living in polluted cities, hundreds of academics and health professionals have tried to put their finger on what external factors might be playing a role in children’s poor health.

Few researchers have looked to see whether there may be a story to tell about links with a child’s ethnicity and whether certain ethnic groups are at higher risk of wheezing illnesses. But now, as part of a wide-ranging ethnicity research project, a team based at the ESRC International Centre for Lifecourse Studies at UCL has been doing just that, as Lidia Panico explains.

About one in five British children has been diagnosed with asthma by a doctor, according to figures from the Health Survey for England, which also shows that wheezing is most common among Black Caribbean children, while Bangladeshi and Black African children suffer least.

A systematic review of UK studies has also found that South Asian children have lower rates of asthma and wheezing illnesses than the general population. In the US, Black children are twice as likely to suffer from asthma than White children. So why do these ethnic differences exist and can they inform our efforts to tackle the problem?

There are quite a few challenges around research in this area and real evidence is thin on the ground, especially when it comes to very young children. Studies have tended to group children from different ethnic backgrounds together or focus only on school age children. Numbers aside, very few studies have been able to go a step further and try to look at what might be behind any observed differences.

Background and biological factors

In our research, we made use of the Millennium Cohort Study, which has been following the health and development of some 20,000 children born in the UK around the turn of the century. This fantastic study has lots of data. This enabled us to look at a host of background and biological factors that might be at play. We looked at the children when they turned 3 years old.

We were able to look at household income, whether mum and dad had jobs and what those jobs were, mum’s age when she gave birth to the child and whether mum lived on her own.

When it came to potential biological causes, we could look to see if parents were smokers, whether the child shared his or her home with other siblings, potentially increasing the risk of catching common infections, furry pets and whether the child had been breastfed.

Other things taken into consideration were whether English was spoken at home and parents’ migration status.

Survey respondents (usually the mother) were asked whether the child had ever suffered from asthma and whether they had had problems with wheezing in the previous 12 months.

Facts and figures

Around one in ten of the children had suffered from asthma at some point while two in ten had wheezed in the last year. Around a fifth of those who had been wheezy in the last year had had more than four attacks in that period with nearly a quarter of them had their sleep disturbed by wheeze on a weekly basis.

As far as ethnic differences were concerned, Black Caribbeans were around 70 per cent more likely than their White counterparts to have had asthma ( 16.2 per cent compared with 11.6 per cent), while Bangladeshis were much less likely at 5.6 per cent.

When we looked at wheezing in the previous 12 months, more than a quarter of Black Caribbean children had suffered compared with one in five White children, so around 40 per cent more likely. Around half of the disadvantage could be explained by social and economic factors, in particular income and the receipt of benefits.

Once again Bangladeshi children were least likely to have wheezed at less than one in ten , especially if their mother was born abroad and if they were living in a bi-lingual or non-English speaking household.

Black African children had lower asthma and wheezing rates than White children, while Indian and Pakistani children had similar rates to White children.

Lower reported rates

Our research team is inclined to think that the apparent South Asian “advantage” might be due to lower reported rates among the Bangladeshi group and should not be attributed to all Asian groups.

With work in the UK and US suggesting South Asians are more likely to be hospitalised with asthma than White children, there is either a story around levels of severity or under reporting/ under diagnosis among these ethnic groups.

Our data suggests that households that would have the most problems communicating with British health services, (new migrants/those who don’t speak English a home or need the survey translated) are least likely to report asthma and wheeze.

By contrast the Black African group which has a similar migration history to the Bangladeshi group, but where English is spoken more frequently, do not show signs of under-reporting.

Migration status and language are key

In order to avoid potentially misleading reports of low asthma and wheezing illness prevalence in some ethnic groups, we should look carefully at migration history and levels of spoken English, particularly in primary care settings.

Ethnic groups are diverse in terms of the prevalence of asthma and wheezing and in their social and economic profiles.

It is also clear that child health provision needs to be carried out within the unique social, economic and cultural context of each group if progress is to be made.

Further information

Lidia Panico is a researcher based at the French Institute for Demographic Studies.